Strain-insulator.



No. 869,403. PATENTED OCT. 29, 1907. A. ANDERSON.

STRAIN INSULATOR.

xrrmourrou rmm MAR. 2, 1906.

man mm 6d zwzadar UNITED DATENT OFFICE.

ALBERT ANDERSON, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO ALBERT AND J. M.

ANDERSON MANUFACTURING COMPANY, OF BOSTON, MASSAOH USETTS, A CORPO-RATION OF MAINE.

STRAIN-INSULATOR.

Specification of Letters Patent.

Patented Oct. 29, 1907.

To all whom. it may concern:

Be it known that I, ALBERT Axnnnson, a citizen of the United States,residing in Boston, in the county of Suffolk and State of Massachusetts,have invented an .lmprovemcnt in Strain-Insulators, of which thefollowing description, in connection with the accompanying drawings, isa specification, like letters on the drawings representing like parts.

This invention relates to an electric insulator of that class known asstrain insulators, and such as are commonly employed in the overheadelectric railway systerns.

Insulators of the class described, are subjected to severe strains, andthe present invention has for its object to provide an insulator whichis capable of withstanding at maximum strain without impairing theefficiency of the insulation.

The particular features of this invention will be pointed out in theclaims at the end of this specification.

Figure l. is an elevation of a strain insulator embodying thisinvention, and Fig. 2, a longitudinal section with parts in elevation ofthe insulator shown in Fig. 1.

The strain insulator herein shown as embodying this invention consistsof two metallic members, shown as eye-bolts a, I), provided with heads0, d, arranged in line with and separated from each other by insulatingmaterial c; a metallic shell f inclosing the heads c, 1, and providedwith openings through which the shanks of the members a, I), extend andfrom which the said shell is separated by insulating material g. Themetallic shell f and the shanks of the bolts for a portion of theirlength are enveloped by insulating material 71.

The insulating material marked c, g and it may be of the same or dilrent compositions or kinds, and in the present instance, the insulatingmaterials are represented as of one kind, which is molded into the formof a globe which may be provided as shown with poles or neck portions7.: enveloping the shanks of the eye-bolts and having annular grooves infor the purpose. of shedding the moisture which may run down the globe.

in order to impart to the insulator the property of resisting strains ofmaximum severity, and thereby avoid cracking, separating or otherwiseimpairing the insulation within and without the metallic shell f thelatter is made curved or spherical on its inner surface at the ends orportions through which the eye-bolts pass, so that the said ends willnot yield or move under severe strain.

It is preferred to make the shell spherical in shape both on its innerand outer surfaces and in one piece of steel as re n'esented herein.

The heads 0, (Z of the eye-bolts may and preferably will also be madesubstantially semi-spherical in shape, whereby the curved surface of theheads may cooperate with the curved inner surfaces of the shell, so thatthe strain may be distributed over a substantially large area of theinclosing shell near the diametrically opposite poles or openings insaid shell, thereby increasing the resistance to movement of the wallsof the openings in the shell and thus obtaining an insulator capable ofwithstanding a longitudinal strain of maximum severity, which isespecially desirable in the line equipment of the overhead system ofelectric railways.

It is preferred to make the spherical metallic shell f in one piece ofsteel, and for this purpose a steel cylinder is employed, into which theinsulating materials a, 9, together with the heads 0, (l of the metallicmembers are placed, and which steel shell is then compressed into theform of a sphere as represented in Fig. 2.

The metallic members a, I) are herein represented as eye-bolts, but itwill be understood that the portion which is exterior to the shell f maybe of any other desired or suitable construction.

Claims.

1. In an insulator of the class described, in combination. two metallicmembers provided with heads, insulating material electrically separatingsaid heads, a one piece inclosing metallic shell substantially sphericalin form and provided with openings substantially opposite each other andhaving its inner surface adjacent each of said open ings curved orsubstantially spherical in shape, insulating mail rial separating saidshell from said members, and insul: ing material on the outer surface ofsaid shell, substantially as described.

2. In an insulator 015 the class described, in combination, two metallicmembers provided with substantially semisphcrical heads. insulatingmaterial electrically separating said heads, a one piece metallic shellsubstantially spher ical in form nndinclosing said heads and providedwith openings substantially opposite each other through which saidmembers extend, said shell having; its inner surface adjacent each ofsaid openings substantially semi-spherical in shape. insulating materialseparating said shell from said members, and insulating material on theouter surface or said shell, substantially as described.

3. I11 an insulator oi the cla described. in combination, a one piecemetal shell substantially spherical in form and provided withsubstz'intially diametrically opposite openings and having a curvedinner surface adjacent to each 01' said openings. metallic membersprovided with heads located within said shell and with shanks extendedthrough said openings, and insulating material within said shellseparating szlid metallic members from each other and from said shell.substantially as described.

I. In an insulator of the class described, in combination, a one-piecesubstantially spherical metallic shell provided with substantiallydiametrically opposite openings, devices provided with heads located insaid shell and with shanks extended through said openings. andinsulating" material separating said heads from each other and from saidshell, substantially as described.

5. In an insulator of the class described, in combination, a onepieccsubstantially spherical metallic shell provided with substantiallydiametrically opposite openings, metallie members provided with curvedheads located in said shell and provided with shanks extended throughsaid openings. and insulating material separating said heads from eachother and from said shell, substantially as described.

6. In an insulator of the class described, in combination, a one-piecesubstantially spherical steel shell provided with substantiallydiametrically Opposite openings, metallic members having curved headslocated in said shell and with shanks extended through said openings,and insulatin: material separating said heads from each other and 10from said shell. substantially as described.

t. In an insulator of the class described. in combination, a one piecesubstantially spherical metal shell provided

